The magnesium status of soil and the magnesium content of cultivated plants

The sample material was collected from cultivated fields without selection based on the magnesium deficiency symptoms observed in the plants. The material consists of 115 samples of the undermost leaves from potato plants, 72 clover and 89 timothy samples, together with corresponding soil samples from the top soil of the fields. The dependence of the magnesium content of the potato leaves, clover and timothy yields on the magnesium content of the soil and its saturation percentage, as well as on the ratio between the exchangeable potassium and magnesium on the equivalent basis, were tested by means of linear regression and correlation analyses. The results obtained show that a highly significant positive correlation prevails between the magnesium saturation percentage of the soil and the magnesium content of potato leaves and timothy. Its effect on the magnesium content of clover could not be determined in the present study. As the amount of exchangeable potassium present in the soil increased in relation to the magnesium, the magnesium content of the studied plants significantly decreased. The material collected for the present investigation revealed that in the case of potato leaves, 51 %, and clover and timothy, 34 %, of the total variations in the magnesium content depended on the magnesium saturation percentage and on the ratio K/Mg in the soil. A rise in the potassium saturation percentage significantly reduced the magnesium content of the clover alone, and taking this into account did not significantly raise the explanation percentage of the total variations in the magnesium content of any of the plants